X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcBinds.lhs;h=e6f78b3eedc21ee63c414019888bf7777bda929d;hb=e7498a3ee1d0484d02a9e86633cc179c76ebf36e;hp=1631365ed65dbc81e30f82cc50d64e98aaf910df;hpb=e7d21ee4f8ac907665a7e170c71d59e13a01da09;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcBinds.lhs b/ghc/compiler/typecheck/TcBinds.lhs index 1631365..e6f78b3 100644 --- a/ghc/compiler/typecheck/TcBinds.lhs +++ b/ghc/compiler/typecheck/TcBinds.lhs @@ -1,75 +1,50 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1995 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996 % \section[TcBinds]{TcBinds} \begin{code} #include "HsVersions.h" -module TcBinds ( - tcTopBindsAndThen, tcLocalBindsAndThen - ) where +module TcBinds ( tcBindsAndThen, tcPragmaSigs ) where ---IMPORT_Trace -- ToDo:rm (debugging) +IMP_Ubiq() -import TcMonad -- typechecking monad machinery -import TcMonadFns ( newLocalsWithOpenTyVarTys, - newLocalsWithPolyTyVarTys, - newSpecPragmaId, newSpecId, - applyTcSubstAndCollectTyVars +import HsSyn ( HsBinds(..), Bind(..), Sig(..), MonoBinds(..), + HsExpr, Match, PolyType, InPat, OutPat(..), + GRHSsAndBinds, ArithSeqInfo, HsLit, Fake, + collectBinders ) +import RnHsSyn ( RenamedHsBinds(..), RenamedBind(..), RenamedSig(..), + RenamedMonoBinds(..), RnName(..) ) -import AbsSyn -- the stuff being typechecked - -import AbsUniType ( isTyVarTy, isGroundTy, isUnboxedDataType, - isGroundOrTyVarTy, extractTyVarsFromTy, - UniType - ) -import BackSubst ( applyTcSubstToBinds ) -import E -import Errors ( topLevelUnboxedDeclErr, specGroundnessErr, - specCtxtGroundnessErr, Error(..), UnifyErrContext(..) - ) -import GenSpecEtc ( checkSigTyVars, genBinds, SignatureInfo(..) ) -import Id ( getIdUniType, mkInstId ) -import IdInfo ( SpecInfo(..) ) -import Inst -import LIE ( nullLIE, mkLIE, plusLIE, LIE ) -import Maybes ( assocMaybe, catMaybes, Maybe(..) ) -import Spec ( specTy ) -import TVE ( nullTVE, TVE(..), UniqFM ) -import TcMonoBnds ( tcMonoBinds ) -import TcPolyType ( tcPolyType ) +import TcHsSyn ( TcHsBinds(..), TcBind(..), TcMonoBinds(..), + TcIdOcc(..), TcIdBndr(..) ) + +import TcMonad hiding ( rnMtoTcM ) +import GenSpecEtc ( checkSigTyVars, genBinds, TcSigInfo(..) ) +import Inst ( Inst, LIE(..), emptyLIE, plusLIE, InstOrigin(..) ) +import TcEnv ( tcExtendLocalValEnv, tcLookupLocalValueOK, newMonoIds ) +IMPORT_DELOOPER(TcLoop) ( tcGRHSsAndBinds ) +import TcMatches ( tcMatchesFun ) +import TcMonoType ( tcPolyType ) +import TcPat ( tcPat ) import TcSimplify ( bindInstsOfLocalFuns ) +import TcType ( newTcTyVar, tcInstSigType ) import Unify ( unifyTauTy ) -import UniqFM ( emptyUFM ) -- profiling, pragmas only -import Util -\end{code} - -%************************************************************************ -%* * -\subsection{Type-checking top-level bindings} -%* * -%************************************************************************ -@tcBindsAndThen@ takes a boolean which indicates whether the binding -group is at top level or not. The difference from inner bindings is -that -\begin{enumerate} -\item -we zero the substitution before each group -\item -we back-substitute after each group. -\end{enumerate} -We still return an LIE, but it is sure to contain nothing but constant -dictionaries, which we resolve at the module level. - -@tcTopBinds@ returns an LVE, not, as you might expect, a GVE. Why? -Because the monomorphism restriction means that is might return some -monomorphic things, with free type variables. Hence it must be an LVE. - -The LIE returned by @tcTopBinds@ may constrain some type variables, -but they are guaranteed to be a subset of those free in the -corresponding returned LVE. +import Kind ( mkBoxedTypeKind, mkTypeKind ) +import Id ( GenId, idType, mkUserId ) +import IdInfo ( noIdInfo ) +import Maybes ( assocMaybe, catMaybes, Maybe(..) ) +import Name ( pprNonSym ) +import PragmaInfo ( PragmaInfo(..) ) +import Pretty +import RnHsSyn ( RnName ) -- instances +import Type ( mkTyVarTy, mkTyVarTys, isTyVarTy, + mkSigmaTy, splitSigmaTy, + splitRhoTy, mkForAllTy, splitForAllTy ) +import Util ( isIn, zipEqual, panic ) +\end{code} %************************************************************************ %* * @@ -77,7 +52,7 @@ corresponding returned LVE. %* * %************************************************************************ -@tcBindsAndThen@ typechecks a @Binds@. The "and then" part is because +@tcBindsAndThen@ typechecks a @HsBinds@. The "and then" part is because it needs to know something about the {\em usage} of the things bound, so that it can create specialisations of them. So @tcBindsAndThen@ takes a function which, given an extended environment, E, typechecks @@ -99,55 +74,28 @@ to the LVE for the following reason. When each individual binding is checked the type of its LHS is unified with that of its RHS; and type-checking the LHS of course requires that the binder is in scope. +At the top-level the LIE is sure to contain nothing but constant +dictionaries, which we resolve at the module level. + \begin{code} -tcBindsAndThen - :: Bool - -> E - -> (TypecheckedBinds -> thing -> thing) -- Combinator - -> RenamedBinds - -> (E -> TcM (thing, LIE, thing_ty)) - -> TcM (thing, LIE, thing_ty) - -tcBindsAndThen top_level e combiner EmptyBinds do_next - = do_next e `thenTc` \ (thing, lie, thing_ty) -> +tcBindsAndThen + :: (TcHsBinds s -> thing -> thing) -- Combinator + -> RenamedHsBinds + -> TcM s (thing, LIE s, thing_ty) + -> TcM s (thing, LIE s, thing_ty) + +tcBindsAndThen combiner EmptyBinds do_next + = do_next `thenTc` \ (thing, lie, thing_ty) -> returnTc (combiner EmptyBinds thing, lie, thing_ty) -tcBindsAndThen top_level e combiner (SingleBind bind) do_next - = tcBindAndThen top_level e combiner bind [] do_next - -tcBindsAndThen top_level e combiner (BindWith bind sigs) do_next - = tcBindAndThen top_level e combiner bind sigs do_next +tcBindsAndThen combiner (SingleBind bind) do_next + = tcBindAndThen combiner bind [] do_next -tcBindsAndThen top_level e combiner (ThenBinds binds1 binds2) do_next - = tcBindsAndThen top_level e combiner binds1 new_after - where - -- new_after :: E -> TcM (thing, LIE, thing_ty) - -- Can't write this signature, cos it's monomorphic in thing and - -- thing_ty. - new_after e = tcBindsAndThen top_level e combiner binds2 do_next -\end{code} +tcBindsAndThen combiner (BindWith bind sigs) do_next + = tcBindAndThen combiner bind sigs do_next -Simple wrappers for export: -\begin{code} -tcTopBindsAndThen - :: E - -> (TypecheckedBinds -> thing -> thing) -- Combinator - -> RenamedBinds - -> (E -> TcM (thing, LIE, anything)) - -> TcM (thing, LIE, anything) - -tcTopBindsAndThen e combiner binds do_next - = tcBindsAndThen True e combiner binds do_next - -tcLocalBindsAndThen - :: E - -> (TypecheckedBinds -> thing -> thing) -- Combinator - -> RenamedBinds - -> (E -> TcM (thing, LIE, thing_ty)) - -> TcM (thing, LIE, thing_ty) - -tcLocalBindsAndThen e combiner binds do_next - = tcBindsAndThen False e combiner binds do_next +tcBindsAndThen combiner (ThenBinds binds1 binds2) do_next + = tcBindsAndThen combiner binds1 (tcBindsAndThen combiner binds2 do_next) \end{code} An aside. The original version of @tcBindsAndThen@ which lacks a @@ -157,31 +105,26 @@ at a different type to the definition itself. There aren't too many examples of this, which is why I thought it worth preserving! [SLPJ] \begin{pseudocode} -tcBindsAndThen - :: Bool -> E -> RenamedBinds - -> (E -> TcM (thing, LIE, thing_ty)) - -> TcM ((TypecheckedBinds, thing), LIE, thing_ty) +tcBindsAndThen + :: RenamedHsBinds + -> TcM s (thing, LIE s, thing_ty)) + -> TcM s ((TcHsBinds s, thing), LIE s, thing_ty) -tcBindsAndThen top_level e EmptyBinds do_next - = do_next e `thenTc` \ (thing, lie, thing_ty) -> +tcBindsAndThen EmptyBinds do_next + = do_next `thenTc` \ (thing, lie, thing_ty) -> returnTc ((EmptyBinds, thing), lie, thing_ty) -tcBindsAndThen top_level e (SingleBind bind) do_next - = tcBindAndThen top_level e bind [] do_next +tcBindsAndThen (SingleBind bind) do_next + = tcBindAndThen bind [] do_next -tcBindsAndThen top_level e (BindWith bind sigs) do_next - = tcBindAndThen top_level e bind sigs do_next +tcBindsAndThen (BindWith bind sigs) do_next + = tcBindAndThen bind sigs do_next -tcBindsAndThen top_level e (ThenBinds binds1 binds2) do_next - = tcBindsAndThen top_level e binds1 new_after +tcBindsAndThen (ThenBinds binds1 binds2) do_next + = tcBindsAndThen binds1 (tcBindsAndThen binds2 do_next) `thenTc` \ ((binds1', (binds2', thing')), lie1, thing_ty) -> returnTc ((binds1' `ThenBinds` binds2', thing'), lie1, thing_ty) - - where - -- new_after :: E -> TcM ((TypecheckedBinds, thing), LIE, thing_ty) - -- Can't write this signature, cos it's monomorphic in thing and thing_ty - new_after e = tcBindsAndThen top_level e binds2 do_next \end{pseudocode} %************************************************************************ @@ -192,350 +135,587 @@ tcBindsAndThen top_level e (ThenBinds binds1 binds2) do_next \begin{code} tcBindAndThen - :: Bool -- At top level - -> E - -> (TypecheckedBinds -> thing -> thing) -- Combinator + :: (TcHsBinds s -> thing -> thing) -- Combinator -> RenamedBind -- The Bind to typecheck -> [RenamedSig] -- ...and its signatures - -> (E -> TcM (thing, LIE, thing_ty)) -- Thing to type check in + -> TcM s (thing, LIE s, thing_ty) -- Thing to type check in -- augmented envt - -> TcM (thing, LIE, thing_ty) -- Results, incl the + -> TcM s (thing, LIE s, thing_ty) -- Results, incl the + +tcBindAndThen combiner bind sigs do_next + = fixTc (\ ~(prag_info_fn, _) -> + -- This is the usual prag_info fix; the PragmaInfo field of an Id + -- is not inspected till ages later in the compiler, so there + -- should be no black-hole problems here. + + tcBindAndSigs binder_names bind + sigs prag_info_fn `thenTc` \ (poly_binds, poly_lie, poly_ids) -> + + -- Extend the environment to bind the new polymorphic Ids + tcExtendLocalValEnv binder_names poly_ids $ -tcBindAndThen top_level e combiner bind sigs do_next - = -- Deal with the bind - tcBind top_level e bind sigs `thenTc` \ (poly_binds, poly_lie, poly_lve) -> + -- Build bindings and IdInfos corresponding to user pragmas + tcPragmaSigs sigs `thenTc` \ (prag_info_fn, prag_binds, prag_lie) -> -- Now do whatever happens next, in the augmented envt - do_next (growE_LVE e poly_lve) `thenTc` \ (thing, thing_lie, thing_ty) -> + do_next `thenTc` \ (thing, thing_lie, thing_ty) -> + + -- Create specialisations of functions bound here + bindInstsOfLocalFuns (prag_lie `plusLIE` thing_lie) + poly_ids `thenTc` \ (lie2, inst_mbinds) -> + + -- All done let - bound_ids = map snd poly_lve + final_lie = lie2 `plusLIE` poly_lie + final_binds = poly_binds `ThenBinds` + SingleBind (NonRecBind inst_mbinds) `ThenBinds` + prag_binds in - -- Create specialisations - specialiseBinds bound_ids thing_lie poly_binds poly_lie - `thenNF_Tc` \ (final_binds, final_lie) -> - -- All done - returnTc (combiner final_binds thing, final_lie, thing_ty) + returnTc (prag_info_fn, (combiner final_binds thing, final_lie, thing_ty)) + ) `thenTc` \ (_, result) -> + returnTc result + where + binder_names = collectBinders bind + + +tcBindAndSigs binder_rn_names bind sigs prag_info_fn + = let + binder_names = map de_rn binder_rn_names + de_rn (RnName n) = n + in + recoverTc ( + -- If typechecking the binds fails, then return with each + -- binder given type (forall a.a), to minimise subsequent + -- error messages + newTcTyVar mkBoxedTypeKind `thenNF_Tc` \ alpha_tv -> + let + forall_a_a = mkForAllTy alpha_tv (mkTyVarTy alpha_tv) + poly_ids = [ mkUserId name forall_a_a (prag_info_fn name) + | name <- binder_names] + in + returnTc (EmptyBinds, emptyLIE, poly_ids) + ) $ + + -- Create a new identifier for each binder, with each being given + -- a type-variable type. + newMonoIds binder_rn_names kind (\ mono_ids -> + tcTySigs sigs `thenTc` \ sig_info -> + tc_bind bind `thenTc` \ (bind', lie) -> + returnTc (mono_ids, bind', lie, sig_info) + ) + `thenTc` \ (mono_ids, bind', lie, sig_info) -> + + -- Notice that genBinds gets the old (non-extended) environment + genBinds binder_names mono_ids bind' lie sig_info prag_info_fn + where + kind = case bind of + NonRecBind _ -> mkTypeKind -- Recursive, so no unboxed types + RecBind _ -> mkBoxedTypeKind -- Non-recursive, so we permit unboxed types \end{code} + +=========== \begin{code} -tcBind :: Bool -> E - -> RenamedBind -> [RenamedSig] - -> TcM (TypecheckedBinds, LIE, LVE) -- LIE is a fixed point of substitution +{- -tcBind False e bind sigs -- Not top level - = tcBind_help False e bind sigs +data SigInfo + = SigInfo RnName + (TcIdBndr s) -- Polymorpic version + (TcIdBndr s) -- Monomorphic verstion + [TcType s] [TcIdOcc s] -- Instance information for the monomorphic version -tcBind True e bind sigs -- Top level! - = pruneSubstTc (tvOfE e) ( - -- DO THE WORK - tcBind_help True e bind sigs `thenTc` \ (new_binds, lie, lve) -> -{- Top-level unboxed values are now allowed - They will be lifted by the Desugarer (see CoreLift.lhs) + -- Deal with type signatures + tcTySigs sigs `thenTc` \ sig_infos -> + let + sig_binders = [binder | SigInfo binder _ _ _ _ <- sig_infos] + poly_sigs = [(name,poly) | SigInfo name poly _ _ _ <- sig_infos] + mono_sigs = [(name,mono) | SigInfo name _ mono _ _ <- sig_infos] + nosig_binders = binders `minusList` sig_binders + in - -- CHECK FOR PRIMITIVE TOP-LEVEL BINDS - listTc [ checkTc (isUnboxedDataType (getIdUniType id)) - (topLevelUnboxedDeclErr id (getSrcLoc id)) - | (_,id) <- lve ] `thenTc_` --} - -- Back-substitute over the binds, since we are about to discard - -- a good chunk of the substitution. - applyTcSubstToBinds new_binds `thenNF_Tc` \ final_binds -> + -- Typecheck the binding group + tcExtendLocalEnv poly_sigs ( + newMonoIds nosig_binders kind (\ nosig_local_ids -> + tcMonoBinds mono_sigs mono_binds `thenTc` \ binds_w_lies -> + returnTc (nosig_local_ids, binds_w_lies) + )) `thenTc` \ (nosig_local_ids, binds_w_lies) -> - -- The lie is already a fixed point of the substitution; it just turns out - -- that almost always this happens automatically, and so we made it part of - -- the specification of genBinds. - returnTc (final_binds, lie, lve) - ) + + -- Decide what to generalise over + getImplicitStuffToGen sig_ids binds_w_lies + `thenTc` \ (tyvars_not_to_gen, tyvars_to_gen, lie_to_gen) -> + + + *** CHECK FOR UNBOXED TYVARS HERE! *** + + + + -- Make poly_ids for all the binders that don't have type signatures + let + tys_to_gen = mkTyVarTys tyvars_to_gen + dicts_to_gen = map instToId (bagToList lie_to_gen) + dict_tys = map tcIdType dicts_to_gen + + mk_poly binder local_id = mkUserId (getName binder) ty noPragmaInfo + where + ty = mkForAllTys tyvars_to_gen $ + mkFunTys dict_tys $ + tcIdType local_id + + more_sig_infos = [ SigInfo binder (mk_poly binder local_id) + local_id tys_to_gen dicts_to_gen lie_to_gen + | (binder, local_id) <- zipEqual "???" nosig_binders nosig_local_ids + ] + + all_sig_infos = sig_infos ++ more_sig_infos -- Contains a "signature" for each binder + in + + + -- Now generalise the bindings + let + -- local_binds is a bunch of bindings of the form + -- f_mono = f_poly tyvars dicts + -- one for each binder, f, that lacks a type signature. + -- This bunch of bindings is put at the top of the RHS of every + -- binding in the group, so as to bind all the f_monos. + + local_binds = [ (local_id, mkHsDictApp (mkHsTyApp (HsVar local_id) tys_to_gen) dicts_to_gen) + | local_id <- nosig_local_ids + ] + + find_sig lid = head [ (pid, tvs, ds, lie) + | SigInfo _ pid lid' tvs ds lie, + lid==lid' + ] + + gen_bind (bind, lie) + = tcSimplifyWithExtraGlobals tyvars_not_to_gen tyvars_to_gen avail lie + `thenTc` \ (lie_free, dict_binds) -> + returnTc (AbsBind tyvars_to_gen_here + dicts + (zipEqual "gen_bind" local_ids poly_ids) + (dict_binds ++ local_binds) + bind, + lie_free) + where + local_ids = bindersOf bind + local_sigs = [sig | sig@(SigInfo _ _ local_id _ _) <- all_sig_infos, + local_id `elem` local_ids + ] + + (tyvars_to_gen_here, dicts, avail) + = case (local_ids, sigs) of + + ([local_id], [SigInfo _ _ _ tyvars_to_gen dicts lie]) + -> (tyvars_to_gen, dicts, lie) + + other -> (tyvars_to_gen, dicts, avail) \end{code} +@getImplicitStuffToGen@ decides what type variables +and LIE to generalise over. + +For a "restricted group" -- see the monomorphism restriction +for a definition -- we bind no dictionaries, and +remove from tyvars_to_gen any constrained type variables + +*Don't* simplify dicts at this point, because we aren't going +to generalise over these dicts. By the time we do simplify them +we may well know more. For example (this actually came up) + f :: Array Int Int + f x = array ... xs where xs = [1,2,3,4,5] +We don't want to generate lots of (fromInt Int 1), (fromInt Int 2) +stuff. If we simplify only at the f-binding (not the xs-binding) +we'll know that the literals are all Ints, and we can just produce +Int literals! + +Find all the type variables involved in overloading, the "constrained_tyvars" +These are the ones we *aren't* going to generalise. +We must be careful about doing this: + (a) If we fail to generalise a tyvar which is not actually + constrained, then it will never, ever get bound, and lands + up printed out in interface files! Notorious example: + instance Eq a => Eq (Foo a b) where .. + Here, b is not constrained, even though it looks as if it is. + Another, more common, example is when there's a Method inst in + the LIE, whose type might very well involve non-overloaded + type variables. + (b) On the other hand, we mustn't generalise tyvars which are constrained, + because we are going to pass on out the unmodified LIE, with those + tyvars in it. They won't be in scope if we've generalised them. + +So we are careful, and do a complete simplification just to find the +constrained tyvars. We don't use any of the results, except to +find which tyvars are constrained. + \begin{code} -tcBind_help top_level e bind sigs - = -- Create an LVE binding each identifier to an appropriate type variable - new_locals binders `thenNF_Tc` \ bound_ids -> - let lve = binders `zip` bound_ids in - - -- Now deal with type signatures, if any - tcSigs e lve sigs `thenTc` \ sig_info -> - - -- Check the bindings: this is the point at which we can use - -- error recovery. If checking the bind fails we just - -- return the empty bindings. The variables will still be in - -- scope, but bound to completely free type variables, which - -- is just what we want to minimise subsequent error messages. - recoverTc (NonRecBind EmptyMonoBinds, nullLIE) - (tc_bind (growE_LVE e lve) bind) `thenNF_Tc` \ (bind', lie) -> - - -- Notice that genBinds gets the old (non-extended) environment - genBinds top_level e bind' lie lve sig_info `thenTc` \ (binds', lie, lve) -> - - -- Add bindings corresponding to SPECIALIZE pragmas in the code - mapAndUnzipTc (doSpecPragma e lve) (get_spec_pragmas sig_info) - `thenTc` \ (spec_binds_s, spec_lie_s) -> - - returnTc (binds' `ThenBinds` (SingleBind (NonRecBind ( - foldr AndMonoBinds EmptyMonoBinds spec_binds_s))), - lie `plusLIE` (foldr plusLIE nullLIE spec_lie_s), - lve) +getImplicitStuffToGen is_restricted sig_ids binds_w_lies + | isUnRestrictedGroup tysig_vars bind + = tcSimplify tyvars_to_gen lie `thenTc` \ (_, _, dicts_to_gen) -> + returnNF_Tc (emptyTyVarSet, tyvars_to_gen, dicts_to_gen) + + | otherwise + = tcSimplify tyvars_to_gen lie `thenTc` \ (_, _, constrained_dicts) -> + let + -- ASSERT: dicts_sig is already zonked! + constrained_tyvars = foldBag unionTyVarSets tyVarsOfInst emptyTyVarSet constrained_dicts + reduced_tyvars_to_gen = tyvars_to_gen `minusTyVarSet` constrained_tyvars + in + returnTc (constrained_tyvars, reduced_tyvars_to_gen, emptyLIE) + where - binders = collectBinders bind + sig_vars = [sig_var | (TySigInfo sig_var _ _ _ _) <- ty_sigs] + + (tyvars_to_gen, lie) = foldBag (\(tv1,lie2) (tv2,lie2) -> (tv1 `unionTyVarSets` tv2, + lie1 `plusLIE` lie2)) + get + (emptyTyVarSet, emptyLIE) + binds_w_lies + get (bind, lie) + = case bindersOf bind of + [local_id] | local_id `in` sig_ids -> -- A simple binding with + -- a type signature + (emptyTyVarSet, emptyLIE) + + local_ids -> -- Complex binding or no type sig + (foldr (unionTyVarSets . tcIdType) emptyTyVarSet local_ids, + lie) +-} +\end{code} + + + +\begin{code} +tc_bind :: RenamedBind -> TcM s (TcBind s, LIE s) + +tc_bind (NonRecBind mono_binds) + = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) -> + returnTc (NonRecBind mono_binds2, lie) + +tc_bind (RecBind mono_binds) + = tcMonoBinds mono_binds `thenTc` \ (mono_binds2, lie) -> + returnTc (RecBind mono_binds2, lie) +\end{code} + +\begin{code} +tcMonoBinds :: RenamedMonoBinds -> TcM s (TcMonoBinds s, LIE s) + +tcMonoBinds EmptyMonoBinds = returnTc (EmptyMonoBinds, emptyLIE) + +tcMonoBinds (AndMonoBinds mb1 mb2) + = tcMonoBinds mb1 `thenTc` \ (mb1a, lie1) -> + tcMonoBinds mb2 `thenTc` \ (mb2a, lie2) -> + returnTc (AndMonoBinds mb1a mb2a, lie1 `plusLIE` lie2) + +tcMonoBinds bind@(PatMonoBind pat grhss_and_binds locn) + = tcAddSrcLoc locn $ + + -- LEFT HAND SIDE + tcPat pat `thenTc` \ (pat2, lie_pat, pat_ty) -> + + -- BINDINGS AND GRHSS + tcGRHSsAndBinds grhss_and_binds `thenTc` \ (grhss_and_binds2, lie, grhss_ty) -> + + -- Unify the two sides + tcAddErrCtxt (patMonoBindsCtxt bind) $ + unifyTauTy pat_ty grhss_ty `thenTc_` + + -- RETURN + returnTc (PatMonoBind pat2 grhss_and_binds2 locn, + plusLIE lie_pat lie) + +tcMonoBinds (FunMonoBind name inf matches locn) + = tcAddSrcLoc locn $ + tcLookupLocalValueOK "tcMonoBinds" name `thenNF_Tc` \ id -> + tcMatchesFun name (idType id) matches `thenTc` \ (matches', lie) -> + returnTc (FunMonoBind (TcId id) inf matches' locn, lie) +\end{code} + +%************************************************************************ +%* * +\subsection{Signatures} +%* * +%************************************************************************ + +@tcSigs@ checks the signatures for validity, and returns a list of +{\em freshly-instantiated} signatures. That is, the types are already +split up, and have fresh type variables installed. All non-type-signature +"RenamedSigs" are ignored. + +\begin{code} +tcTySigs :: [RenamedSig] -> TcM s [TcSigInfo s] + +tcTySigs (Sig v ty _ src_loc : other_sigs) + = tcAddSrcLoc src_loc ( + tcPolyType ty `thenTc` \ sigma_ty -> + tcInstSigType sigma_ty `thenNF_Tc` \ sigma_ty' -> + let + (tyvars', theta', tau') = splitSigmaTy sigma_ty' + in + + tcLookupLocalValueOK "tcSig1" v `thenNF_Tc` \ val -> + unifyTauTy (idType val) tau' `thenTc_` + + returnTc (TySigInfo val tyvars' theta' tau' src_loc) + ) `thenTc` \ sig_info1 -> + + tcTySigs other_sigs `thenTc` \ sig_infos -> + returnTc (sig_info1 : sig_infos) + +tcTySigs (other : sigs) = tcTySigs sigs +tcTySigs [] = returnTc [] +\end{code} + + +%************************************************************************ +%* * +\subsection{SPECIALIZE pragmas} +%* * +%************************************************************************ + - new_locals binders - = case bind of - NonRecBind _ -> -- Recursive, so no unboxed types - newLocalsWithOpenTyVarTys binders +@tcPragmaSigs@ munches up the "signatures" that arise through *user* +pragmas. It is convenient for them to appear in the @[RenamedSig]@ +part of a binding because then the same machinery can be used for +moving them into place as is done for type signatures. + +\begin{code} +tcPragmaSigs :: [RenamedSig] -- The pragma signatures + -> TcM s (Name -> PragmaInfo, -- Maps name to the appropriate PragmaInfo + TcHsBinds s, + LIE s) + +tcPragmaSigs sigs = returnTc ( \name -> NoPragmaInfo, EmptyBinds, emptyLIE ) + +{- +tcPragmaSigs sigs + = mapAndUnzip3Tc tcPragmaSig sigs `thenTc` \ (names_w_id_infos, binds, lies) -> + let + name_to_info name = foldr ($) noIdInfo + [info_fn | (n,info_fn) <- names_w_id_infos, n==name] + in + returnTc (name_to_info, + foldr ThenBinds EmptyBinds binds, + foldr plusLIE emptyLIE lies) +\end{code} - RecBind _ -> -- Non-recursive, so we permit unboxed types - newLocalsWithPolyTyVarTys binders +Here are the easy cases for tcPragmaSigs - get_spec_pragmas sig_info - = catMaybes (map get_pragma_maybe sig_info) - where - get_pragma_maybe s@(ValSpecInfo _ _ _ _) = Just s - get_pragma_maybe _ = Nothing +\begin{code} +tcPragmaSig (DeforestSig name loc) + = returnTc ((name, addInfo DoDeforest),EmptyBinds,emptyLIE) +tcPragmaSig (InlineSig name loc) + = returnTc ((name, addInfo_UF (iWantToBeINLINEd UnfoldAlways)), EmptyBinds, emptyLIE) +tcPragmaSig (MagicUnfoldingSig name string loc) + = returnTc ((name, addInfo_UF (mkMagicUnfolding string)), EmptyBinds, emptyLIE) \end{code} +The interesting case is for SPECIALISE pragmas. There are two forms. +Here's the first form: \begin{verbatim} f :: Ord a => [a] -> b -> b {-# SPECIALIZE f :: [Int] -> b -> b #-} \end{verbatim} -We generate: + +For this we generate: \begin{verbatim} - f@Int = /\ b -> let d1 = ... - in f Int b d1 + f* = /\ b -> let d1 = ... + in f Int b d1 +\end{verbatim} +where f* is a SpecPragmaId. The **sole** purpose of SpecPragmaIds is to +retain a right-hand-side that the simplifier will otherwise discard as +dead code... the simplifier has a flag that tells it not to discard +SpecPragmaId bindings. - h :: Ord a => [a] -> b -> b - {-# SPECIALIZE h :: [Int] -> b -> b #-} +In this case the f* retains a call-instance of the overloaded +function, f, (including appropriate dictionaries) so that the +specialiser will subsequently discover that there's a call of @f@ at +Int, and will create a specialisation for @f@. After that, the +binding for @f*@ can be discarded. - spec_h = /\b -> h [Int] b dListOfInt - ^^^^^^^^^^^^^^^^^^^^ This bit created by specId +The second form is this: +\begin{verbatim} + f :: Ord a => [a] -> b -> b + {-# SPECIALIZE f :: [Int] -> b -> b = g #-} \end{verbatim} -\begin{code} -doSpecPragma :: E -> LVE - -> SignatureInfo - -> TcM (TypecheckedMonoBinds, LIE) +Here @g@ is specified as a function that implements the specialised +version of @f@. Suppose that g has type (a->b->b); that is, g's type +is more general than that required. For this we generate +\begin{verbatim} + f@Int = /\b -> g Int b + f* = f@Int +\end{verbatim} -doSpecPragma e lve (ValSpecInfo name spec_ty using src_loc) - = let - main_id = assoc "doSpecPragma" lve name - -- Get the parent Id; it should exist (renamer promises...). +Here @f@@Int@ is a SpecId, the specialised version of @f@. It inherits +f's export status etc. @f*@ is a SpecPragmaId, as before, which just serves +to prevent @f@@Int@ from being discarded prematurely. After specialisation, +if @f@@Int@ is going to be used at all it will be used explicitly, so the simplifier can +discard the f* binding. + +Actually, there is really only point in giving a SPECIALISE pragma on exported things, +and the simplifer won't discard SpecIds for exporte things anyway, so maybe this is +a bit of overkill. - main_id_ty = getIdUniType main_id - main_id_free_tyvars = extractTyVarsFromTy main_id_ty - origin = ValSpecOrigin name src_loc - err_ctxt = ValSpecSigCtxt name spec_ty src_loc +\begin{code} +tcPragmaSig (SpecSig name poly_ty maybe_spec_name src_loc) + = tcAddSrcLoc src_loc $ + tcAddErrCtxt (valSpecSigCtxt name spec_ty) $ + + -- Get and instantiate its alleged specialised type + tcPolyType poly_ty `thenTc` \ sig_sigma -> + tcInstSigType sig_sigma `thenNF_Tc` \ sig_ty -> + let + (sig_tyvars, sig_theta, sig_tau) = splitSigmaTy sig_ty + origin = ValSpecOrigin name in - addSrcLocTc src_loc ( - specTy origin spec_ty `thenNF_Tc` \ (spec_tyvars, spec_dicts, spec_tau) -> -- Check that the SPECIALIZE pragma had an empty context - checkTc (not (null spec_dicts)) + checkTc (null sig_theta) (panic "SPECIALIZE non-empty context (ToDo: msg)") `thenTc_` - -- Make an instance of this id - specTy origin main_id_ty `thenNF_Tc` \ (main_tyvars, main_dicts, main_tau) -> + -- Get and instantiate the type of the id mentioned + tcLookupLocalValueOK "tcPragmaSig" name `thenNF_Tc` \ main_id -> + tcInstSigType [] (idType main_id) `thenNF_Tc` \ main_ty -> + let + (main_tyvars, main_rho) = splitForAllTy main_ty + (main_theta,main_tau) = splitRhoTy main_rho + main_arg_tys = mkTyVarTys main_tyvars + in -- Check that the specialised type is indeed an instance of - -- the inferred type. - -- The unification should leave all type vars which are - -- currently free in the environment still free, and likewise - -- the signature type vars. - -- The only way type vars free in the envt could possibly be affected - -- is if main_id_ty has free type variables. So we just extract them, - -- and check that they are not constrained in any way by the unification. - applyTcSubstAndCollectTyVars main_id_free_tyvars `thenNF_Tc` \ free_tyvars' -> - unifyTauTy spec_tau main_tau err_ctxt `thenTc_` - checkSigTyVars [] (spec_tyvars ++ free_tyvars') - spec_tau main_tau err_ctxt `thenTc_` + -- the type of the main function. + unifyTauTy sig_tau main_tau `thenTc_` + checkSigTyVars sig_tyvars sig_tau `thenTc_` -- Check that the type variables of the polymorphic function are -- either left polymorphic, or instantiate to ground type. -- Also check that the overloaded type variables are instantiated to -- ground type; or equivalently that all dictionaries have ground type - applyTcSubstToTyVars main_tyvars `thenNF_Tc` \ main_arg_tys -> - applyTcSubstToInsts main_dicts `thenNF_Tc` \ main_dicts' -> - - checkTc (not (all isGroundOrTyVarTy main_arg_tys)) - (specGroundnessErr err_ctxt main_arg_tys) - `thenTc_` + mapTc zonkTcType main_arg_tys `thenNF_Tc` \ main_arg_tys' -> + zonkTcThetaType main_theta `thenNF_Tc` \ main_theta' -> + tcAddErrCtxt (specGroundnessCtxt main_arg_tys') + (checkTc (all isGroundOrTyVarTy main_arg_tys')) `thenTc_` + tcAddErrCtxt (specContextGroundnessCtxt main_theta') + (checkTc (and [isGroundTy ty | (_,ty) <- theta'])) `thenTc_` - checkTc (not (and [isGroundTy ty | (_,ty) <- map getDictClassAndType main_dicts'])) - (specCtxtGroundnessErr err_ctxt main_dicts') - `thenTc_` + -- Build the SpecPragmaId; it is the thing that makes sure we + -- don't prematurely dead-code-eliminate the binding we are really interested in. + newSpecPragmaId name sig_ty `thenNF_Tc` \ spec_pragma_id -> -- Build a suitable binding; depending on whether we were given -- a value (Maybe Name) to be used as the specialisation. case using of - Nothing -> + Nothing -> -- No implementation function specified + + -- Make a Method inst for the occurrence of the overloaded function + newMethodWithGivenTy (OccurrenceOf name) + (TcId main_id) main_arg_tys main_rho `thenNF_Tc` \ (lie, meth_id) -> - -- Make a specPragmaId to which to bind the new call-instance - newSpecPragmaId name spec_ty Nothing - `thenNF_Tc` \ pseudo_spec_id -> let - pseudo_bind = VarMonoBind pseudo_spec_id pseudo_rhs - pseudo_rhs = mkTyLam spec_tyvars (mkDictApp (mkTyApp (Var main_id) main_arg_tys) - (map mkInstId main_dicts')) + pseudo_bind = VarMonoBind spec_pragma_id pseudo_rhs + pseudo_rhs = mkHsTyLam sig_tyvars (HsVar (TcId meth_id)) in - returnTc (pseudo_bind, mkLIE main_dicts') + returnTc (pseudo_bind, lie, \ info -> info) - Just spec_name -> -- use spec_name as the specialisation value ... - let - spec_id = lookupE_Value e spec_name - spec_id_ty = getIdUniType spec_id + Just spec_name -> -- Use spec_name as the specialisation value ... - spec_id_free_tyvars = extractTyVarsFromTy spec_id_ty - spec_id_ctxt = ValSpecSpecIdCtxt name spec_ty spec_name src_loc + -- Type check a simple occurrence of the specialised Id + tcId spec_name `thenTc` \ (spec_body, spec_lie, spec_tau) -> - spec_tys = map maybe_ty main_arg_tys - maybe_ty ty | isTyVarTy ty = Nothing - | otherwise = Just ty - in - -- Make an instance of the spec_id - specTy origin spec_id_ty `thenNF_Tc` \ (spec_id_tyvars, spec_id_dicts, spec_id_tau) -> - - -- Check that the specialised type is indeed an instance of - -- the type inferred for spec_id - -- The unification should leave all type vars which are - -- currently free in the environment still free, and likewise - -- the signature type vars. - -- The only way type vars free in the envt could possibly be affected - -- is if spec_id_ty has free type variables. So we just extract them, - -- and check that they are not constrained in any way by the unification. - applyTcSubstAndCollectTyVars spec_id_free_tyvars `thenNF_Tc` \ spec_id_free_tyvars' -> - unifyTauTy spec_tau spec_id_tau spec_id_ctxt `thenTc_` - checkSigTyVars [] (spec_tyvars ++ spec_id_free_tyvars') - spec_tau spec_id_tau spec_id_ctxt `thenTc_` - - -- Check that the type variables of the explicit spec_id are - -- either left polymorphic, or instantiate to ground type. - -- Also check that the overloaded type variables are instantiated to - -- ground type; or equivalently that all dictionaries have ground type - applyTcSubstToTyVars spec_id_tyvars `thenNF_Tc` \ spec_id_arg_tys -> - applyTcSubstToInsts spec_id_dicts `thenNF_Tc` \ spec_id_dicts' -> - - checkTc (not (all isGroundOrTyVarTy spec_id_arg_tys)) - (specGroundnessErr spec_id_ctxt spec_id_arg_tys) - `thenTc_` - - checkTc (not (and [isGroundTy ty | (_,ty) <- map getDictClassAndType spec_id_dicts'])) - (specCtxtGroundnessErr spec_id_ctxt spec_id_dicts') - `thenTc_` + -- Check that it has the correct type, and doesn't constrain the + -- signature variables at all + unifyTauTy sig_tau spec_tau `thenTc_` + checkSigTyVars sig_tyvars sig_tau `thenTc_` -- Make a local SpecId to bind to applied spec_id - newSpecId main_id spec_tys spec_ty `thenNF_Tc` \ local_spec_id -> - - -- Make a specPragmaId id with a spec_info for local_spec_id - -- This is bound to local_spec_id - -- The SpecInfo will be extracted by the specialiser and - -- used to create a call instance for main_id (which is - -- extracted from the spec_id) - -- NB: the pseudo_local_id must stay in the scope of main_id !!! - let - spec_info = SpecInfo spec_tys (length main_dicts') local_spec_id - in - newSpecPragmaId name spec_ty (Just spec_info) `thenNF_Tc` \ pseudo_spec_id -> + newSpecId main_id main_arg_tys sig_ty `thenNF_Tc` \ local_spec_id -> + let - spec_bind = VarMonoBind local_spec_id spec_rhs - spec_rhs = mkTyLam spec_tyvars (mkDictApp (mkTyApp (Var spec_id) spec_id_arg_tys) - (map mkInstId spec_id_dicts')) - pseudo_bind = VarMonoBind pseudo_spec_id (Var local_spec_id) + spec_rhs = mkHsTyLam sig_tyvars spec_body + spec_binds = VarMonoBind local_spec_id spec_rhs + `AndMonoBinds` + VarMonoBind spec_pragma_id (HsVar (TcId local_spec_id)) + spec_info = SpecInfo spec_tys (length main_theta) local_spec_id in - returnTc (spec_bind `AndMonoBinds` pseudo_bind, mkLIE spec_id_dicts') - ) + returnTc ((name, addInfo spec_info), spec_binds, spec_lie) +-} \end{code} -\begin{code} -tc_bind :: E - -> RenamedBind - -> TcM (TypecheckedBind, LIE) -tc_bind e (NonRecBind mono_binds) - = tcMonoBinds e mono_binds `thenTc` \ (mono_binds2, lie) -> - returnTc (NonRecBind mono_binds2, lie) +%************************************************************************ +%* * +\subsection[TcBinds-monomorphism]{The monomorphism restriction} +%* * +%************************************************************************ -tc_bind e (RecBind mono_binds) - = tcMonoBinds e mono_binds `thenTc` \ (mono_binds2, lie) -> - returnTc (RecBind mono_binds2, lie) -\end{code} +Not exported: \begin{code} -specialiseBinds - :: [Id] -- Ids bound in this group - -> LIE -- LIE of scope of these bindings - -> TypecheckedBinds - -> LIE - -> NF_TcM (TypecheckedBinds, LIE) - -specialiseBinds bound_ids lie_of_scope poly_binds poly_lie - = bindInstsOfLocalFuns lie_of_scope bound_ids - `thenNF_Tc` \ (lie2, inst_mbinds) -> - - returnNF_Tc (poly_binds `ThenBinds` (SingleBind (NonRecBind inst_mbinds)), - lie2 `plusLIE` poly_lie) +isUnRestrictedGroup :: [TcIdBndr s] -- Signatures given for these + -> TcBind s + -> Bool + +isUnRestrictedGroup sigs EmptyBind = True +isUnRestrictedGroup sigs (NonRecBind monobinds) = isUnResMono sigs monobinds +isUnRestrictedGroup sigs (RecBind monobinds) = isUnResMono sigs monobinds + +is_elem v vs = isIn "isUnResMono" v vs + +isUnResMono sigs (PatMonoBind (VarPat (TcId v)) _ _) = v `is_elem` sigs +isUnResMono sigs (PatMonoBind other _ _) = False +isUnResMono sigs (VarMonoBind (TcId v) _) = v `is_elem` sigs +isUnResMono sigs (FunMonoBind _ _ _ _) = True +isUnResMono sigs (AndMonoBinds mb1 mb2) = isUnResMono sigs mb1 && + isUnResMono sigs mb2 +isUnResMono sigs EmptyMonoBinds = True \end{code} + %************************************************************************ %* * -\subsection{Signatures} +\subsection[TcBinds-errors]{Error contexts and messages} %* * %************************************************************************ -@tcSigs@ checks the signatures for validity, and returns a list of -{\em freshly-instantiated} signatures. That is, the types are already -split up, and have fresh type variables (not @TyVarTemplate@s) -installed. \begin{code} -tcSigs :: E -> LVE - -> [RenamedSig] - -> TcM [SignatureInfo] - -tcSigs e lve [] = returnTc [] - -tcSigs e lve (s:ss) - = tc_sig s `thenTc` \ sig_info1 -> - tcSigs e lve ss `thenTc` \ sig_info2 -> - returnTc (sig_info1 : sig_info2) +patMonoBindsCtxt bind sty + = ppHang (ppPStr SLIT("In a pattern binding:")) 4 (ppr sty bind) + +-------------------------------------------- +specContextGroundnessCtxt -- err_ctxt dicts sty + = panic "specContextGroundnessCtxt" +{- + = ppHang ( + ppSep [ppBesides [ppStr "In the SPECIALIZE pragma for `", ppr sty name, ppStr "'"], + ppBesides [ppStr " specialised to the type `", ppr sty spec_ty, ppStr "'"], + pp_spec_id sty, + ppStr "... not all overloaded type variables were instantiated", + ppStr "to ground types:"]) + 4 (ppAboves [ppCat [ppr sty c, ppr sty t] + | (c,t) <- map getDictClassAndType dicts]) where - tc_sig (Sig v ty _ src_loc) -- no interesting pragmas on non-iface sigs - = addSrcLocTc src_loc ( - - babyTcMtoTcM - (tcPolyType (getE_CE e) (getE_TCE e) nullTVE ty) `thenTc` \ sigma_ty -> - - let val = assoc "tcSigs" lve v in - -- (The renamer/dependency-analyser should have ensured - -- that there are only signatures for which there is a - -- corresponding binding.) - - -- Instantiate the type, and unify with the type variable - -- found in the Id. - specTy SignatureOrigin sigma_ty `thenNF_Tc` \ (tyvars, dicts, tau_ty) -> - unifyTauTy (getIdUniType val) tau_ty - (panic "ToDo: unifyTauTy(tcSigs)") `thenTc_` - - returnTc (TySigInfo val tyvars dicts tau_ty src_loc) - ) - - tc_sig (SpecSig v ty using src_loc) - = addSrcLocTc src_loc ( - - babyTcMtoTcM - (tcPolyType (getE_CE e) (getE_TCE e) nullTVE ty) `thenTc` \ sigma_ty -> - - returnTc (ValSpecInfo v sigma_ty using src_loc) - ) + (name, spec_ty, locn, pp_spec_id) + = case err_ctxt of + ValSpecSigCtxt n ty loc -> (n, ty, loc, \ x -> ppNil) + ValSpecSpecIdCtxt n ty spec loc -> + (n, ty, loc, + \ sty -> ppBesides [ppStr "... type of explicit id `", ppr sty spec, ppStr "'"]) +-} - tc_sig (InlineSig v guide locn) - = returnTc (ValInlineInfo v guide locn) +----------------------------------------------- +specGroundnessCtxt + = panic "specGroundnessCtxt" - tc_sig (DeforestSig v locn) - = returnTc (ValDeforestInfo v locn) - tc_sig (MagicUnfoldingSig v str locn) - = returnTc (ValMagicUnfoldingInfo v str locn) +valSpecSigCtxt v ty sty + = ppHang (ppPStr SLIT("In a SPECIALIZE pragma for a value:")) + 4 (ppSep [ppBeside (pprNonSym sty v) (ppPStr SLIT(" ::")), + ppr sty ty]) \end{code} +